Inflationary cosmology from STM theory of gravity

I study the power-law and de Sitter expansions for the universe during inflation from the STM theory of gravity. In a de Sitter expansion the additional dimension is related to the cosmological constant. I find from experimental data that the mass of the inflaton field is $m^2=2/(3\Psi^2)$. In power-law expansion, the fifth coordinate appears to be a dimensionless constant. The interesting here is that the $\Psi$-value depends on the initial conditions. I find the 5D line element for this inflationary expansion, which is a function of the classical component of the inflaton.